March 24 (UPI) -- London's Metropolitan Police on Friday said officers made "two further significant arrests" overnight in their investigation of an attack near Parliament that killed four victims and the assailant.
In a press conference Friday morning, Met Police Acting Deputy Commissioner Mark Rowley also identified the Westminster attacker by his birthname: Adrian Russell Ajao.
Rowley said a total of 10 people have been detained, including one woman was released on bail. Authorities have carried out at least 21 searches and seized more than 2,700 items including "massive of amounts of computer data."
"To that end in our continuing investigation and ongoing covert activity, we have made two further significant arrests overnight -- one in the West Midlands and one in North West," Rowley said during a press conference, referring to official regions in England north of London.
Rowley also identified the fourth victim who died from his injuries while hospitalized as 75-year-old Leslie Rhodes from Streatham in south London.
There are two people hospitalized in critical condition, one in a life-threatening condition and two police officers who sustained injuries, Rowley said, adding that a total of at least 50 people were injured with 31 needing hospitalization.
Rowley said that though there is no further evidence of threats, investigators are moving to focus on understanding the attacker's motivation, preparation and to see if he had associates -- specifically, if he acted alone and was inspired by terrorist propaganda, or if he was encouraged, supported or directed by others.
"At this point I want to appeal specifically to the public. We remain keen to hear from anyone who knew Khalid Masood well; understands who his associates were; and can provide with information about places he has recently visited," Rowley said. "There might well be people out there who did have concerns about Masood but weren't sure or didn't feel comfortable for whatever reason in passing information to us."
Armed officers patrolling London have nearly doubled since the attack, Rowley added.
Investigators said Masood, 52, was shot dead by responding police at the gates of British Parliament on Wednesday after he struck several people with his vehicle on the nearby Westminster Bridge in an attack claimed by the Islamic State militant group.
Masood killed three people before he was shot -- two pedestrians on the bridge and a police officer at the Westminster gates. The victims are Rhodes, who later died, Police Constable Keith Palmer, 48, British citizen Aysha Frade, 43, and U.S. citizen Kurt Cochran, 54, of Utah.
Authorities said Masood had prior convictions for violent offenses, including grievous bodily harm and assault, but was never convicted of terror crimes. His first criminal conviction occurred in 1983 for criminal damage and his most recent was in 2003 for possession of a knife, police said.
The attack, which is being investigated as a terrorist incident, on Wednesday is Britain's deadliest since the July 7, 2005, terrorist bombings in central London that killed 52 people and injured nearly 800.
Rowley said that despite the attempt, terrorists targeting London would not succeed. On Thursday, hundreds gathered to hold a vigil to pay tribute to the victims of the attack.
"Finally, last night a true cross section of people came together to stand together to remember -- but also to send a message. A strong message -- to those inspired by hate and extremism of all persuasions that we will not give in to those who seek to breed discord and fear," Rowley said. "This is as true now as it has ever been. Our acting commissioner, Craig Mackey, told thousands who gathered in central London last night terrorist have tried to tear this city apart before and they have never succeeded. The very fact London has gone back to work and so many were happy to gather in central London last night shows they have failed again.